yeah my friend and I built a few boxes. If you make it out of plywood it'll sound like shit. My friend and I did a lot of custom stuff with the box as far as shape and what not. A helpful tip that helped us. If you want to conserve weight you don't have to make the WHOLE box out of MDF. Just make a smaller box to fit inside the custom inclosure to hold the sub out of MDF. Then you can get the sound of an MDF box and the weight and versatility of a plywood one. It'll save a lot of weight and money. Also just like spyder posted, audio places will sell the carpet.